Thirteen T cell hybridomas and two cell lines expressing gammadelta TcR were generated from splenic T cells. At least three different types of gamma-chains (Vgamma2-Cgamma1,Cgamma2 and Cgamma4) were shown to be expressed by these cells. Analysis of Vdelta gene expression revealed that Vdelta5 gene segments are used by 53% of the cells in our panel. Other Vdelta segments expressed by our panel of cells were Vdelta2, Vdelta4, Vdelta6, and Valpha10, indicating that the Vdelta repertoire expressed in the spleen is similar, but possibly not identical to the adult thymus repertoire. Sequence analysis of the V-D-J joinings of the delta-chain messages revealed substantial diversity, indicating that the delta-chain a significant portion of the potential diversity predicated for these chains. The subunit interactions within the alpha/beta and gamma/delta T cell receptor-CD3 (TcR-CD3) complexes were compared. Both complexes contain at least seven chains: alphabeta and gammadelta T cell receptor chains plus five CD3 chains (gammadeltaepsilonzeta2). It was found that in both TcR- CD3 complexes analogous subunit interactions could be defined: CD3gamma and CD3delta each form a stable complex with separate CD3epsilon chains. Both the TcR gamma/delta and TcR alpha/beta form stable receptor complexes with these CD3 gamma/epsilon and CD3 delta/epsilon subunits. A zeta2 homodimer is present in these TcR-CD3 complexes. Cross-linking results indicated that the TcR beta and delta chains are each others structural homologs or that in TcR-CD3 complexes both TcR chains (alpha and beta, gamma and delta) are spatially closely associated with the CD3gamma chain. The identical subunit interactions in the alpha/beta and gamma/delta TcR-CD3 complexes indicate no large structural differences between these receptor complexes. Evidence that the vitronectin receptor (VNR) is expressed on lymphoid cells was obtained. VNR was shown to be expressed on a variety of T cell lines, tumors, and Con A-activated splenocytes, but not resting T cells, and is capable of binding to the extracellular matrix proteins fibronectin, fibrinogen, and vitronectin, via the tripeptide sequence RGD. In view of recent studies demonstrating that this molecule functions as an accessory molecule in T cell activation, the VNR may play an important role in mouse T cell functions.